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Pedzinski T, Grzyb K, Kaźmierczak F, Frański R, Filipiak P, Marciniak B. Early Events of Photosensitized Oxidation of Sulfur-Containing Amino Acids Studied by Laser Flash Photolysis and Mass Spectrometry. J Phys Chem B 2020; 124:7564-7573. [PMID: 32790392 PMCID: PMC7498160 DOI: 10.1021/acs.jpcb.0c06008] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
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The
mechanism of photooxidation of methionine (N-Ac-Met-NH-CH3, 1) and methyl-cysteine (N-Ac-MeCys-NH-CH3, 2) analogues by 3-carboxybenzophenone triplet
(3CB*) in neutral aqueous solution was studied using techniques of
nanosecond laser flash photolysis and steady-state photolysis. The
short-lived transients derived from 3CB and sulfur-containing amino
acids were identified, and their quantum yields and kinetics of formation
and decay were determined. The stable photoproducts were analyzed
using liquid chromatography coupled with high-resolution mass spectrometry.
Substantial differences in the mechanisms were found for methionine
and S-methyl-cysteine analogues for both primary
and secondary photoreactions. A new secondary reaction channel (back
hydrogen atom transfer from the ketyl radical to the carbon-centered
α-thioalkyl radical yielding reactants in the ground states)
was suggested. The detailed mechanisms of 3CB* sensitized photooxidation
of 1 and 2 are proposed and discussed.
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Affiliation(s)
- Tomasz Pedzinski
- Center for Advanced Technology, Adam Mickiewicz University, 10 Uniwersytetu Poznanskiego Str., 61-614 Poznan, Poland.,Faculty of Chemistry, Adam Mickiewicz University, 8 Uniwersytetu Poznanskiego Str., 61-614 Poznan, Poland
| | - Katarzyna Grzyb
- Faculty of Chemistry, Adam Mickiewicz University, 8 Uniwersytetu Poznanskiego Str., 61-614 Poznan, Poland
| | - Franciszek Kaźmierczak
- Faculty of Chemistry, Adam Mickiewicz University, 8 Uniwersytetu Poznanskiego Str., 61-614 Poznan, Poland
| | - Rafał Frański
- Faculty of Chemistry, Adam Mickiewicz University, 8 Uniwersytetu Poznanskiego Str., 61-614 Poznan, Poland
| | - Piotr Filipiak
- Center for Advanced Technology, Adam Mickiewicz University, 10 Uniwersytetu Poznanskiego Str., 61-614 Poznan, Poland.,Faculty of Chemistry, Adam Mickiewicz University, 8 Uniwersytetu Poznanskiego Str., 61-614 Poznan, Poland
| | - Bronislaw Marciniak
- Center for Advanced Technology, Adam Mickiewicz University, 10 Uniwersytetu Poznanskiego Str., 61-614 Poznan, Poland.,Faculty of Chemistry, Adam Mickiewicz University, 8 Uniwersytetu Poznanskiego Str., 61-614 Poznan, Poland
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